Earlier I posted some info regarding a bug in Exchange 2003 when updating the Recipient Policies. There's one other little gotcha I discovered this morning.
During the install of Exchange 2003, the default SMTP domain for the \Exchange virtual directory in IIS is set to equal the default SMTP address in the "Default Policy" recipient policy. If a user does not have an SMTP address with this domain, you cannot open their OWA explicitly using just their alias, you must use one of their SMTP addresses.
i.e. http://exchangeserver/exchange/first.last@domain.com works but http://exchangeserver/exchange/FLast won't work.
It's hard to catch this because most users who use OWA will just open http://exchangeserver/exchange and it will work for them. You can also still access another user's mailbox via MAPI just fine. This issue only shows up when opening another user's mailbox in OWA explicitly.
So, the fix? Either change the default SMTP address in the Default Policy to match a domain that all mailboxes have, or make sure all mailboxes have an smtp address in the domain of the default SMTP address in the Default Policy.
You can find more information in the following Microsoft KB article. http://support.microsoft.com/kb/293386
Don't forget that changing this stuff can lead to the bug found in my earlier post.
